一种低轨遥感卫星按需数据传输机制

针对现有低轨（LEO）遥感卫星数据下行机制普遍存在的低效率、高时延、传输路径易损等问题，提出了一种新型的遥感数据传输机制。所提机制中，支持地面站按需实时定位遥感影像资源，并建立定位卫星到达地面站的传输路径；在建立传输路径时，考虑到协作卫星与地面的可视时间有限，提出了以路径持续服务时间最大化为度量的路由算法，降低因协作卫星改变而引入的传输时延。基于NS3仿真平台实现了所设计的数据传输机制，实验表明，提出机制相比现有数据传输机制可降低数据传输时延，减少数据丢失。 

An on-demand data transmission mechanism for LEO remote sensing satellite

Aimed at the shortcomings of the existing data downlink mechanisms for low earth orbit (LEO) remote sensing satellite, such as low effiency, high delay and vulnerable transmission path, a new remote sensing data transmission mechanism was proposed. In the proposed mechanism, earth stations were supported to locate remote sensing image resources in real time on demand, and in the process, the transmission path from the positioning satellite to earth station was established. Taking into account the limited visual time between the cooperative satellite and the earth station, when transmission path is established, a routing algorithm was proposed based on the maximization of the path persistent service time to reduce the transmission delay caused by the change of the cooperative satellite. The designed data transmission mechanism was implemented based on the NS3 simulation platform. The experimental results show that the proposed mechanism can reduce the data transmission delay and data loss compared with the existing data transmission mechanism.